/*
* Given a path to a jre to execute, this routine checks if this process
* is indeed that jre. If not, it exec's that jre.
*
* We want to actually check the paths rather than just the version string
* built into the executable, so that given version specification will yield
* the exact same Java environment, regardless of the version of the arbitrary
* launcher we start with.
*/
void
ExecJRE(char *jre, char **argv) {
int len;
char path[MAXPATHLEN + 1];
const char *progname = GetProgramName();
/*
* Resolve the real path to the currently running launcher.
*/
len = GetModuleFileName(NULL, path, MAXPATHLEN + 1);
if (len == 0 || len > MAXPATHLEN) {
JLI_ReportErrorMessageSys(JRE_ERROR9, progname);
exit(1);
}
JLI_TraceLauncher("ExecJRE: old: %s\n", path);
JLI_TraceLauncher("ExecJRE: new: %s\n", jre);
/*
* If the path to the selected JRE directory is a match to the initial
* portion of the path to the currently executing JRE, we have a winner!
* If so, just return.
*/
if (JLI_StrNCaseCmp(jre, path, JLI_StrLen(jre)) == 0)
return; /* I am the droid you were looking for */
/*
* If this isn't the selected version, exec the selected version.
*/
JLI_Snprintf(path, sizeof(path), "%s\\bin\\%s.exe", jre, progname);
/*
* Although Windows has an execv() entrypoint, it doesn't actually
* overlay a process: it can only create a new process and terminate
* the old process. Therefore, any processes waiting on the initial
* process wake up and they shouldn't. Hence, a chain of pseudo-zombie
* processes must be retained to maintain the proper wait semantics.
* Fortunately the image size of the launcher isn't too large at this
* time.
*
* If it weren't for this semantic flaw, the code below would be ...
*
* execv(path, argv);
* JLI_ReportErrorMessage("Error: Exec of %s failed\n", path);
* exit(1);
*
* The incorrect exec semantics could be addressed by:
*
* exit((int)spawnv(_P_WAIT, path, argv));
*
* Unfortunately, a bug in Windows spawn/exec impementation prevents
* this from completely working. All the Windows POSIX process creation
* interfaces are implemented as wrappers around the native Windows
* function CreateProcess(). CreateProcess() takes a single string
* to specify command line options and arguments, so the POSIX routine
* wrappers build a single string from the argv[] array and in the
* process, any quoting information is lost.
*
* The solution to this to get the original command line, to process it
* to remove the new multiple JRE options (if any) as was done for argv
* in the common SelectVersion() routine and finally to pass it directly
* to the native CreateProcess() Windows process control interface.
*/
{
char *cmdline;
char *p;
char *np;
char *ocl;
char *ccl;
char *unquoted;
DWORD exitCode;
STARTUPINFO si;
PROCESS_INFORMATION pi;
/*
* The following code block gets and processes the original command
* line, replacing the argv[0] equivalent in the command line with
* the path to the new executable and removing the appropriate
* Multiple JRE support options. Note that similar logic exists
* in the platform independent SelectVersion routine, but is
* replicated here due to the syntax of CreateProcess().
*
* The magic "+ 4" characters added to the command line length are
* 2 possible quotes around the path (argv[0]), a space after the
* path and a terminating null character.
*/
ocl = GetCommandLine();
np = ccl = JLI_StringDup(ocl);
p = nextarg(&np); /* Discard argv[0] */
cmdline = (char *)JLI_MemAlloc(JLI_StrLen(path) + JLI_StrLen(np) + 4);
if (JLI_StrChr(path, (int)' ') == NULL && JLI_StrChr(path, (int)'\t') == NULL)
cmdline = JLI_StrCpy(cmdline, path);
else
cmdline = JLI_StrCat(JLI_StrCat(JLI_StrCpy(cmdline, "\""), path), "\"");
while (*np != (char)0) { /* While more command-line */
p = nextarg(&np);
if (*p != (char)0) { /* If a token was isolated */
unquoted = unquote(p);
if (*unquoted == '-') { /* Looks like an option */
if (JLI_StrCmp(unquoted, "-classpath") == 0 ||
JLI_StrCmp(unquoted, "-cp") == 0) { /* Unique cp syntax */
cmdline = JLI_StrCat(JLI_StrCat(cmdline, " "), p);
p = nextarg(&np);
if (*p != (char)0) /* If a token was isolated */
cmdline = JLI_StrCat(JLI_StrCat(cmdline, " "), p);
} else if (JLI_StrNCmp(unquoted, "-version:", 9) != 0 &&
JLI_StrCmp(unquoted, "-jre-restrict-search") != 0 &&
JLI_StrCmp(unquoted, "-no-jre-restrict-search") != 0) {
cmdline = JLI_StrCat(JLI_StrCat(cmdline, " "), p);
}
} else { /* End of options */
cmdline = JLI_StrCat(JLI_StrCat(cmdline, " "), p);
cmdline = JLI_StrCat(JLI_StrCat(cmdline, " "), np);
JLI_MemFree((void *)unquoted);
break;
}
JLI_MemFree((void *)unquoted);
}
}
JLI_MemFree((void *)ccl);
if (JLI_IsTraceLauncher()) {
np = ccl = JLI_StringDup(cmdline);
p = nextarg(&np);
printf("ReExec Command: %s (%s)\n", path, p);
printf("ReExec Args: %s\n", np);
JLI_MemFree((void *)ccl);
}
(void)fflush(stdout);
(void)fflush(stderr);
/*
* The following code is modeled after a model presented in the
* Microsoft Technical Article "Moving Unix Applications to
* Windows NT" (March 6, 1994) and "Creating Processes" on MSDN
* (Februrary 2005). It approximates UNIX spawn semantics with
* the parent waiting for termination of the child.
*/
memset(&si, 0, sizeof(si));
si.cb =sizeof(STARTUPINFO);
memset(&pi, 0, sizeof(pi));
if (!CreateProcess((LPCTSTR)path, /* executable name */
(LPTSTR)cmdline, /* command line */
(LPSECURITY_ATTRIBUTES)NULL, /* process security attr. */
(LPSECURITY_ATTRIBUTES)NULL, /* thread security attr. */
(BOOL)TRUE, /* inherits system handles */
(DWORD)0, /* creation flags */
(LPVOID)NULL, /* environment block */
(LPCTSTR)NULL, /* current directory */
(LPSTARTUPINFO)&si, /* (in) startup information */
(LPPROCESS_INFORMATION)&pi)) { /* (out) process information */
JLI_ReportErrorMessageSys(SYS_ERROR1, path);
exit(1);
}
if (WaitForSingleObject(pi.hProcess, INFINITE) != WAIT_FAILED) {
if (GetExitCodeProcess(pi.hProcess, &exitCode) == FALSE)
exitCode = 1;
} else {
JLI_ReportErrorMessage(SYS_ERROR2);
exitCode = 1;
}
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
exit(exitCode);
}
}
/*
* 使用指定的jvm版本来运行java程序
*
* ******************************************************************************
* 函数原型： char *realpath(const char *path, char *resolved_path);
* 函数说明： 用来将参数path所指的相对路径转换成绝对路径后存于参数resolved_path所指的字符串数组或指针中
* 函数返回： 成功则返回指向resolved_path的指针，失败返回NULL，错误代码存于errno
*
* ******************************************************************************
* 函数原型: int execve(const char * filename,char * const argv[],char * const envp[]);
* 函数说明： execve用来执行参数filename字符串所代表的文件路径,第二个参数是利用数组指针来传递给执行文件,并且需要以
* 空指针(NULL)结束,最后一个参数则为传递给执行文件的新环境变量数组.exec函数一共有六个,其中execve为内核
* 级系统调用,其他(execl,execle,execlp,execv,execvp)都是调用execve的库函数
* 函数返回： 如果执行成功则函数不会返回,执行失败则直接返回-1,失败原因存于errno中
*/
void ExecJRE(char *jre, char **argv)
{
char wanted[PATH_MAX];
const char* progname = GetProgramName();
const char* execname = NULL;
/*
* 转换成绝对路径
*/
if (realpath(jre, wanted) == NULL) {
JLI_ReportErrorMessage(JRE_ERROR9, jre);
exit(1);
}
/*
* 获取启动当前JVM进程的命令
*/
SetExecname(argv);
execname = GetExecName();
if (execname == NULL) {
JLI_ReportErrorMessage(JRE_ERROR10);
exit(1);
}
/*
* If the path to the selected JRE directory is a match to the initial
* portion of the path to the currently executing JRE, we have a winner!
* If so, just return.
*/
if (JLI_StrNCmp(wanted, execname, JLI_StrLen(wanted)) == 0)
return; /* I am the droid you were looking for */
/*
* This should never happen (because of the selection code in SelectJRE),
* but check for "impossibly" long path names just because buffer overruns
* can be so deadly.
*/
if (JLI_StrLen(wanted) + JLI_StrLen(progname) + 6 > PATH_MAX) {
JLI_ReportErrorMessage(JRE_ERROR11);
exit(1);
}
/*
* Construct the path and exec it.
*/
(void)JLI_StrCat(JLI_StrCat(wanted, "/bin/"), progname);
argv[0] = JLI_StringDup(progname);
if (JLI_IsTraceLauncher()) {
int i;
printf("ReExec Command: %s (%s)\n", wanted, argv[0]);
printf("ReExec Args:");
for (i = 1; argv[i] != NULL; i++)
printf(" %s", argv[i]);
printf("\n");
}
JLI_TraceLauncher("TRACER_MARKER:About to EXEC\n");
//刷当前进程的标准输出/错误输出流
(void)fflush(stdout);
(void)fflush(stderr);
//执行新的可执行程序
execv(wanted, argv);
JLI_ReportErrorMessageSys(JRE_ERROR12, wanted);
exit(1);
}
static jboolean
GetPublicJREHome(char *buf, jint bufsize)
{
HKEY key, subkey;
char version[MAXPATHLEN];
/*
* Note: There is a very similar implementation of the following
* registry reading code in the Windows java control panel (javacp.cpl).
* If there are bugs here, a similar bug probably exists there. Hence,
* changes here require inspection there.
*/
/* Find the current version of the JRE */
if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, JRE_KEY, 0, KEY_READ, &key) != 0) {
JLI_ReportErrorMessage(REG_ERROR1, JRE_KEY);
return JNI_FALSE;
}
if (!GetStringFromRegistry(key, "CurrentVersion",
version, sizeof(version))) {
JLI_ReportErrorMessage(REG_ERROR2, JRE_KEY);
RegCloseKey(key);
return JNI_FALSE;
}
if (JLI_StrCmp(version, GetDotVersion()) != 0) {
JLI_ReportErrorMessage(REG_ERROR3, JRE_KEY, version, GetDotVersion()
);
RegCloseKey(key);
return JNI_FALSE;
}
/* Find directory where the current version is installed. */
if (RegOpenKeyEx(key, version, 0, KEY_READ, &subkey) != 0) {
JLI_ReportErrorMessage(REG_ERROR1, JRE_KEY, version);
RegCloseKey(key);
return JNI_FALSE;
}
if (!GetStringFromRegistry(subkey, "JavaHome", buf, bufsize)) {
JLI_ReportErrorMessage(REG_ERROR4, JRE_KEY, version);
RegCloseKey(key);
RegCloseKey(subkey);
return JNI_FALSE;
}
if (JLI_IsTraceLauncher()) {
char micro[MAXPATHLEN];
if (!GetStringFromRegistry(subkey, "MicroVersion", micro,
sizeof(micro))) {
printf("Warning: Can't read MicroVersion\n");
micro[0] = '\0';
}
printf("Version major.minor.micro = %s.%s\n", version, micro);
}
RegCloseKey(key);
RegCloseKey(subkey);
return JNI_TRUE;
}
